JPH03968A - Fuel supply device - Google Patents

Abstract

PURPOSE:To improve the measurement accuracy of the required fuel flow rate corresponding to an intake air flow rate by providing the upstream side of a fuel passage opening for a fuel measurement means attached to the subject device with an adjustment means for supplying the predetermined flow rate while increasing or decreasing the flow rate, depending upon the open area of the aforesaid passage. CONSTITUTION:A fuel measurement means for measuring the required fuel flow rate obtained on the basis of intake manifold pressure B and engine speed D has a mechanical pressure adjustment means 2 with the internal space thereof divided into an upstream chamber 3, a negative pressure chamber 4, an atmospheric pressure chamber 6 and a downstream chamber 8 with the first and second diaphragms 5 and 9. In addition, a connection rod 10 for connecting the aforesaid diaphragms 5 and 9 to each other is fitted with a valve 10a for opening and closing a fuel inlet 3a. The upstream and downstream chambers 3 and 8 are made continuous to each other via a fuel passage 12, and the area A of opening 12a of the passage 12 is controlled with a solenoid valve 13. In this case, an adjustment means 16 controlled depending upon the aforesaid area A is provided for feeding the predetermined flow rate to the upstream chamber 3 via a route separate from the measurement flow rate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel supply system equipped with a fuel meter 1 means for measuring the flow rate of fuel to be supplied in accordance with the intake air flow l in an internal combustion engine.

[Conventional technology]

For example, the present applicant has proposed a multi-point fuel injection device that discharges the fuel flow rate measured based on the fuel metering (control) means as described above from the fuel injection valves arranged for each cylinder of the engine. Proposed Act 1-149
There is one described in No. 5. This device has a first flow path for returning fuel from a constant flow rate supply means to a fuel supply source via first and second jets and a regulator, and a second flow path that is branched from this flow path on the upstream side of the second jet. One of the above-mentioned fuel metering means is arranged, and the fuel pressure in the flow path on the upstream side of the fuel metering means is adjusted by measuring the fuel flow rate corresponding to the detected intake air flow rate and returning it to the fuel supply source. This fuel pressure is applied to the upper chamber of the fuel injector of each cylinder, and a portion of the constant fuel flow flowing through the lower chamber is applied to the upper chamber from the lower chamber, which is separated by a diaphragm, to increase the fuel pressure in the upper chamber. The injected fuel is injected into the manifold of each cylinder according to the intake air flow rate, and the flow rate of the injected fuel is controlled to an amount corresponding to the intake air flow rate, so that the air-fuel ratio of the air-fuel mixture is maintained constant.

By the way, the fuel flow rate required by the engine is proportional to the product of engine rotation speed and intake manifold air density, but considering that air density can be substituted for pressure, the fuel flow rate required by the engine is determined by measuring intake manifold pressure and engine rotation speed. The above-mentioned fuel measuring means for measuring the fuel flow rate has been proposed by the present applicant in Japanese Patent Application No. 1-60069.

This fuel metering means will be explained with reference to FIG. In the fuel metering means 1, 2 is a mechanical pressure adjustment means, and 3 is an inlet port 3.
4 is a negative pressure chamber separated from the upstream chamber 3 by a first diaphragm 5 and to which the intake manifold pressure P is applied; 6 is a negative pressure chamber by an inner wall 7; 4 and the atmospheric pressure P. 8 is a downstream chamber separated from the atmospheric pressure chamber 6 by a second diaphragm 9, and 10 is a small hole 7 in the inner wall 7.
a connecting rod that connects the two diaphragms 5 and 9 and is formed with a valve 10a that controls opening and closing of the inlet 3a; 11 is a spring that presses the second diaphragm 9 in the opening direction of the valve 10a; 12; is a fuel passage that communicates the upstream chamber 3 and the lower seven flow chambers 8.

13 is a solenoid valve that can increase or decrease the area A of the opening 12a of the fuel passage 12 by, for example, duty control; 14 is a control signal that increases or decreases the opening area A in accordance with the input engine speed; This is a control circuit (ECU) that causes the solenoid valve 13 to output. Then, the engine speed can be converted to the opening area A by the solenoid valve 13, and the manifold pressure can be converted to the fuel pressure difference (P, -P, ) before and after the solenoid valve 13, respectively.

When the engine is operated with the above-described configuration, the opening area A of the opening 12a is determined by the solenoid valve 13 according to the engine speed, and the manifold pressure P is applied to the negative pressure chamber 4. As the first and second diaphragms 5 and 9 are displaced, the opening amount of the valve 10a is adjusted, and the pressure difference (P, -P2) between the upstream chamber 3 and the downstream chamber 8 is controlled, and the pressure difference (P, -P2) is controlled according to the intake air flow rate. Required fuel flow rate Q'. .

, is measured at the opening 12a, and the pressures applied to both diaphragms 5 and 9 are balanced.

[Problem to be solved by the invention]

Then, when the manifold pressure Pffi changes, the pressure difference (
P, -Pi) change proportionally as shown in FIG. 8(A), but since the flow rate is proportional to the square root of the pressure difference, even if the intake manifold pressure P4 increases, the metered fuel flow rate Q'. , 1 do not increase linearly, but draw a curve as shown in FIG. 8(B). For this reason, a deviation as shown by diagonal lines occurs from the required fuel flow rate shown by the broken line, and this deviation is about 15% at maximum, resulting in a problem that the air-fuel ratio of the air-fuel mixture fluctuates.

In view of such problems, an object of the present invention is to provide a fuel supply device in which the fuel metering accuracy of the fuel metering means is improved.

[Means to solve the problem]

The fuel supply device according to the present invention includes: a first electrical opening area adjustment means for adjusting the opening area of the fuel passage; a control circuit that outputs a control signal that changes the opening area of the fuel passage according to the engine speed; In a fuel supply device equipped with a fuel metering means comprising a mechanical pressure adjusting means for adjusting the fuel pressure difference between upstream and downstream sides of the opening in proportion to the manifold pressure, this fuel metering means is provided on the upstream side of the opening of the fuel passage. Adjustment means is provided for adding a predetermined fuel flow rate that is increased or decreased depending on the opening area.

The adjusting means is connected to the upstream chamber of the mechanical pressure regulating means or the upstream chamber of the first pressure regulator.

The adjustment means is connected to the fuel flow path upstream of the fuel metering means.

The adjustment means has an upper chamber and a royal chamber each having a fuel flow, an inlet and an outlet, which are separated by a diaphragm connected to a valve for controlling the opening and closing of the inlet and communicated through an orifice, and the opening area of the orifice is The aperture area is configured to be changed by two electrical aperture area adjustment means.

The first and second electrical aperture area adjustment means may be controlled by the same control signal.

The adjustment means is connected to a fuel flow path upstream of the fuel metering means;
A third electrical aperture area adjustment provided in a bypass passage connecting this flow passage and a constant flow rate fuel flow passage that communicates via a jet, and that changes the opening area of another jet in this passage based on a control signal. It is composed of means.

[For production]

The opening area of the fuel passage is adjusted according to the engine speed, and according to this opening area, a predetermined fuel flow rate is added to the upstream side of the opening by the adjusting means, and the manifold pressure is converted into differential pressure across the opening. By causing the total amount of the predetermined flow rate and the total flow rate to flow through the opening, the fuel flow rate is adjusted according to the intake air flow rate which is proportional to the manifold pressure.
It can be detected as the fuel pressure upstream of the fuel metering means.

A predetermined flow rate is applied to the upstream chamber and manifold pressure is applied to the negative pressure chamber, displacing the first and second diaphragms to establish a pressure difference between the upstream chamber and the downstream chamber.

A predetermined flow rate is added to the upstream side of the fuel metering means, and the total amount with the metered flow rate flows into the upstream chamber and flows through the opening.

A predetermined flow rate of the adjusting means is controlled by the control signal.

The third electrical opening area adjusting means is controlled by the control signal, and the predetermined flow rate is combined with the metered flow rate and supplied to the upstream chamber.

〔Example〕

An embodiment of the present invention will be described below based on FIG. 1 and FIG. 2, and the same reference numerals will be used for the same parts as in the above-mentioned prior art, and the explanation thereof will be omitted.

In the figure, 16 indicates a predetermined fuel flow rate Q2, a measured flow rate Q611
1 is an adjustment means that feeds the fuel into the upstream chamber 3 of the mechanical pressure adjustment means 2 through a flow path different from Q2, and this flow path Q2 is designed to constantly flow through the opening 12a of the fuel passage 12.

In this adjustment means 16, 17 is an inlet port 17a.
an upper chamber into which fuel is pumped from the fuel supply via the
19 is a lower chamber equipped with an outlet 18a that sends out the fuel flow rate Q2 to the upstream chamber 3 of the mechanical pressure regulating means 2, and 19 is a valve 19a that partitions the upper chamber 17 and the lower chamber 18 and controls the opening amount of the inlet 17a. 20 is a pressure setting spring that presses the diaphragm 19 in the opening direction of the valve 19a, 21 is an orifice that communicates the compartments 17 and 18, and 22 is a diaphragm that controls the opening area of the orifice 21. A second solenoid valve, that is, a second electrical opening area adjusting means, for controlling the fuel flow rate Q2 that passes through the outlet port 18a and is sent out from the outlet 18a, and the predetermined flow rate Q2
For example, the duty is controlled by a control signal from the control circuit 14 so that the aperture area A changes according to the aperture area A of the aperture 12a.

When the manifold pressure P□ is not applied to the mechanical pressure adjustment means 2, the opening 1
The predetermined flow rate Qz is determined according to the size of the opening area A so that the differential pressure (PP2) across the opening 2a becomes a predetermined constant value p (see FIG. 3). That is, the flow rate Q2
Regardless of the size of the flow rate Q2, the differential pressure before and after the flow rate Q2 at the opening 12a is always controlled to a constant value p.

Since the present embodiment is configured as described above, when the manifold pressure P is generated by starting the engine and is applied to the negative pressure chamber 4 of the mechanical pressure adjustment means 2, the first diaphragm 5 and When the valve IOa is displaced downward, the inflow amount Q of fuel from the inlet port 3a. is regulated, and the area A (valve opening rate) of the opening 12a caused by the operation of the solenoid valve 13 is determined based on the engine speed. On the other hand, since the opening area A determines the opening rate of the second solenoid valve 22 of the adjusting means 16, that is, the predetermined flow rate Q2, and the flow is flowing through the opening 12a in advance, the opening 12a of the fuel passage 12
The total fuel flow rate QT measured by flowing through is the sum of the predetermined flow rate Q2 and the metered flow rate Q o u flowing in from the inlet 3a, and the differential pressure across the opening 12a (P, -P,) is equal to this total flow rate. It belongs to QT.

Note that when the flow rate Qa=Qz, the upper chamber 35 and the lower chamber 36 are
The fuel pressure is controlled.

The metered fuel Q7 passes through the opening 12a and flows into the downstream chamber 8, and when the fuel pressure P2 in the downstream chamber 8 increases, the valve 10a moves in the opening direction, but the opening amount of the valve loa increases. When the inflow amount of fuel Q 6 u l increases, the fuel pressure P in the upstream chamber 3 increases, causing the valve 10a to move in the closing direction, and the pressures applied to the first and second diaphragms 5 and 9 are balanced.

Here, out of the total fuel flow rate Q□ measured at the opening 12a,
The flow rate Q2 is a constant flow rate determined by the opening rate of the solenoid valve 13, and the pressure difference p1 before and after it is always constant, so the pressure difference (P
, -P2) and the opening ratio, that is, the opening area A of the solenoid valve 13, which changes depending on the engine speed, determines the required fuel flow rate according to the intake air flow I. . , (=QT−Q,
) can be detected by Therefore, in the fuel flow path of the metered flow rate Q I u l on the upstream side of the mechanical pressure adjustment means 2, the fuel pressure according to the required fuel flow rate can be detected.

Then, when the manifold pressure P□ increases in accordance with the increase in the intake air flow rate, the first diaphragm 5 is displaced upward, the valve IOa is moved in the valve opening direction, and the air flows through the inlet port 3a and flows through the opening 12a. Metering flow ff1Q.

8. increases, and the pressure difference (Pl Pg) is as shown in Figure 8 (A).
Manifold pressure P as shown in . changes in proportion to. In addition, if the engine speed (opening rate of the solenoid valve 13) does not change, the predetermined flow fflQz is constant, so the flow ff1Q and the front and rear differential pressure (
PP2) is obtained. In this case, Q□ is the pressure difference (
As mentioned above, it is proportional to the square root of p, -F2),
In the case of this embodiment, the pressure difference (p, -p,) exceeds p, so the characteristic curve in Fig. 3 is almost a straight line in this part, and the flow rate QT and the pressure difference (p, -p, P, ) exhibits a proportional relationship. Also, intake manifold pressure P□
is taken out as a pressure difference (PP2 p,), and the flow rate Q
o u t and the pressure difference (PI F2 1)-) also exhibit a proportional relationship.

Furthermore, since the flow rate Q2 is a fixed quantity determined by the opening rate of the solenoid valve 13, the flow rate Q, u, which is the difference between the flow rate QT and Q2, is proportional to the pressure difference (P, -F2), that is, the intake manifold pressure P, . The required fuel flow rate Q can be measured as a value depending on the amount of intake air IN.

. The measurement accuracy of No. 1 can be improved.

As described above, according to this embodiment, it is possible to measure the required fuel flow rate proportional to the intake manifold pressure P, , and therefore it is possible to improve the measurement accuracy of the required fuel flow rate in accordance with the intake air flow rate.

In addition, by inputting throttle opening information in addition to the engine speed into the control circuit I4 to correct each control signal and adjust the opening rate of each solenoid valve 13.22, the fuel flow can be adjusted to match the intake air flow rate. The degree of freedom in measuring ff1Q,u can be improved.

FIG. 4 is a schematic sectional view showing a multi-point fuel supply system which is a second embodiment of the fuel supply system according to the present invention.

In the figure, reference numeral 24 indicates constant flow rate supply means for sending out a constant flow rate of fuel sent through a pump 26 from a fuel supply source 25, and 27 indicates a constant flow rate supply means for sending fuel sent out at a constant flow rate through a first jet 28 to a second jet 29 and a second jet 29. a first flow path returning to the fuel supply source 25 via the regulator 30; a second flow path 31 branching from the first flow path 27 on the upstream side of the second jet 29 and merging with the first flow path 27 on the downstream side of the regulator 30; 32 is a fuel metering means provided in the middle of the second flow path 31; 33 is a fuel injection valve provided for each cylinder and provided with an upper chamber 35 and a lower chamber 36 partitioned by a diaphragm 34; The fuel pressure on the upstream side of the fuel metering means 32 is applied to each upper chamber 35, and each lower chamber 36 communicates with an intake manifold 38 of each cylinder via a valve 37. Reference numeral 40 denotes a third flow path through which a constant flow rate of fuel equally distributed by the third jet 41 passes through the lower chamber 36 and the fourth jet 42 and joins the first flow path 27 at the regulator 30; The upstream side, that is, the upper chamber 35 of each fuel injection valve 33, depending on the measured fuel flow rate.
The fuel pressure changes, and a corresponding amount of fuel is injected from the lower chamber 36 to the manifold 38.

Further, 43 is a throttle valve disposed in the intake pipe; 44
is a throttle opening detection means that detects the opening of the throttle valve 43 and inputs the detected opening to the control circuit 14.

Next, the fuel metering means 32 will be explained using the same reference numerals for the same parts as in the first embodiment described above.The mechanical pressure adjusting means 2
consists of a first pressure regulator 45 and a second pressure regulator 46 connected via the fuel passage 12. In the first pressure regulator 45, 47 is a ball valve whose opening amount is controlled by being pressed by a spring 48 in the direction of closing the inlet 3a and pushed by the protrusion of the first diaphragm 5; A spring 50 that presses the first diaphragm 5 in the opening direction of the pawl valve 47 is an adjustment screw. In the second pressure regulator 46, 51 is a spring that presses the second diaphragm 9 into contact with the outlet 8a of the downstream chamber 8, and the fuel pressure P2 in the downstream chamber 8 is controlled to be constant.

The above configuration is similar to the multi-point fuel supply system described in Japanese Patent Application No. 1-60069 mentioned above.

In this embodiment, the adjusting means 16 is connected to the upstream chamber 3 of the first pressure regulator 45 to allow a predetermined flow rate Q2 to flow from the upstream chamber 3 to the opening 12a.

FIG. 5 shows a third embodiment of the present invention. In this embodiment, the adjusting means 16 is located not in the upstream chamber 3 of the first pressure regulator 45 but in the first flow path 27 on the upstream side thereof. (downstream side of the jet 28), and a predetermined flow rate Q2 is made to flow through this flow path 27.

Therefore, the second flow path 31 on the upstream side of this fuel metering means 32
and a predetermined flow rate Q2 and a metered flow rate Q6 in the first flow path 27.
The fuel flow rate QT, which is the sum of u +, flows, but the flow rate QT
=Q, the fuel pressure is balanced such that the amount of injection from the fuel injection valve 33 is 0, so the upper chamber 35 of each fuel injection valve 33 has a metered flow rate Q as in each of the above-described embodiments. . The fuel pressure corresponding to , is detected and applied.

In addition, in the first to third embodiments described above, the predetermined flow fit
Q z and the opening rate of the solenoid valve 13 (opening area A
) are in a proportional relationship, so each gain of the solenoid valve 13 and the second solenoid valve 22 (the rate of change in the opening rate (opening area) of each solenoid valve 13 and 22 relative to the input control signal) must be adjusted appropriately. If selected, each solenoid valve 13.22 can be controlled by the same control signal.

Next, FIG. 6 shows a fourth embodiment of the present invention. In this embodiment, the first jet 2 is bypassed and the first flow path 2 is replaced.
7 (upstream side of the second jet 29) and the third flow path 40 (upstream side of the third jet 41).
A fifth jet 54 is provided at the fifth jet 5.
A third solenoid valve 55, ie, a third electrical opening area adjusting means, is arranged to move back and forth with respect to the opening area of the opening area of the opening area. The opening area of this fifth jet 54 is the control circuit 1
This is determined by, for example, duty-controlling the third solenoid valve 55 using a control signal of No.
A predetermined flow ff1Q2 flowing to the first flow path 27 is controlled.

Therefore, the second flow path 31 and the first flow path 27 on the upstream side of the fuel metering means 32 have a predetermined flow rate Q2 and a measured flow rate Q 6 u I
A fuel flow rate QT, which is the sum of , flows into the upper chamber 35 of each fuel injection valve 33 . 1 is applied.

In the case of this embodiment, the flow rate Q2 changes according to the opening rate of the third solenoid valve 55, but at the same time, the fuel flow rate QL flowing through the third flow path 40 also changes, and the third solenoid valve 55 The valve opening rate is set so that the injection amount characteristic of the fuel injection valve 33 matches the required fuel flow rate. Therefore, unlike the above embodiments, a proportional relationship does not hold between the opening rates (opening area A) of the solenoid valve 13 and the third solenoid valve 55. Therefore, it is necessary for the control circuit 14 to output separate control signals.

Further, the fifth jet 54, the third solenoid valve 55, etc. constitute adjustment means.

〔Effect of the invention〕

As described above, according to the fuel supply device according to the present invention, a predetermined flow rate is supplied to the upstream side of the opening whose area is changed by the first electrical opening area adjustment means by increasing or decreasing the flow rate according to the opening area. Since the adjusting means is provided, the required fuel flow rate proportional to the intake manifold pressure can be measured, and the accuracy of measuring the required fuel flow rate in accordance with the intake air flow rate can be improved.

Furthermore, since two types of electrical aperture area adjusting means can be controlled by the same control signal, control can be simplified and manufacturing costs can be reduced.

[Brief explanation of drawings]

1 to 3 relate to a first embodiment of the fuel supply device according to the present invention, in which FIG. 1 is a schematic cross-sectional view of the fuel metering means, FIG. 2 is a cross-sectional view of the adjusting means, and FIG. The figure is a diagram showing the relationship between the pressure difference and each fuel flow rate according to each opening area, and FIGS. Figure 7 is a schematic cross-sectional view of a fuel metering means according to the prior art, Figure 8 (A) is a diagram showing the relationship between the manifold pressure and the pressure difference between the openings, and (B) is the relationship between the intake manifold pressure, the required fuel flow rate, and the metered flow rate. FIG. l, 32...Fuel metering means, 2...Mechanical pressure adjustment means, 3...Upstream chamber, 4...Negative pressure chamber, 5...
...First diaphragm, 8...Downstream chamber, 9...
・Second diaphragm, 12...Fuel passage, 12a・
...Opening, 13...Solenoid valve, 14...
... Control circuit, 16... Adjustment means, 21...
... Orifice, 22 ... Second solenoid valve,
27...First flow path, 28...First jet, 3
1...Second channel, 40...Third channel, 45...
...First pressure regulator, 46...Second pressure regulator, 53...
・Bypass passage, 54...Fifth jet, 55...
...Third solenoid valve. Go to Wang Shiryu Room 3

Claims (1)

[Scope of Claims] (1) A first electrical opening area adjusting means for adjusting the area of the opening of the fuel passage; and a first electrical opening area adjusting means for adjusting the opening area of the fuel passage; The control circuit includes a control circuit that outputs an output to the opening area adjusting means, and a mechanical pressure adjusting means that adjusts the fuel pressure difference between the upstream side and the downstream side of the first electrical opening area adjusting means in proportion to the intake manifold pressure. In a fuel supply device equipped with a fuel metering means capable of measuring a fuel flow rate corresponding to an intake air flow rate as a fuel pressure on the upstream side thereof, a fuel metering means is provided upstream of an opening of the fuel passage according to an opening area of the passage. 1. A fuel supply device comprising an adjusting means for adding a predetermined fuel flow rate that is increased or decreased. (2) In the fuel metering means, the mechanical pressure regulating means is connected to each other and partitions an upstream chamber and a downstream chamber provided with a fuel inlet from a negative pressure chamber and an atmospheric pressure chamber to which manifold pressure is applied, respectively. The first and second diaphragms, a valve that adjusts the opening amount of the inlet in conjunction with the diaphragm, and a spring that presses the diaphragm in the opening direction of the valve communicate with the upstream chamber and the downstream chamber. 2. The fuel supply device according to claim 1, further comprising: said fuel passageway, said adjustment means being connected to said upstream chamber. (3) In the fuel metering means, the mechanical pressure adjustment means is interlocked with a first diaphragm that partitions an upstream chamber provided with a fuel inlet and a negative pressure chamber to which manifold negative pressure is applied, and the diaphragm. a first pressure regulator comprising a valve that adjusts the opening amount of the inlet, a second diaphragm that partitions a downstream chamber in which a fuel outlet is provided and an atmospheric pressure chamber, and a second diaphragm that closes the outlet. a second pressure regulator comprising a spring that presses the second diaphragm in the direction;
The fuel supply device according to claim (1), wherein the adjustment means is connected to the upstream chamber. (4) The fuel supply according to claim (2) or (3), wherein the adjusting means is connected to a fuel flow path on the upstream side of the fuel metering means instead of the upstream chamber. Device. (5) The adjusting means includes an upper chamber having a fuel inlet, a lower chamber having a fuel outlet, a diaphragm that partitions both chambers and is connected to a valve that controls opening and closing of the inlet, and both chambers. Claims (1) to (4) characterized by comprising: an orifice that communicates with the orifice; and second electrical opening area adjustment means that changes the opening area of the orifice based on a control signal from the control circuit. The fuel supply device according to any one of the above. (6) The fuel supply device according to claim (5), wherein the first and second electrical opening area adjusting means are controlled by the same control signal. (7) In place of the upstream chamber, the adjustment means communicates a fuel flow path on the upstream side of the fuel metering means with a constant flow rate fuel flow path that communicates with the fuel flow path via a jet. and comprises another jet disposed in the bypass passage and a third electrical opening area adjustment means for changing the opening area of the other jet based on a control signal from the control circuit. The fuel supply device according to claim (3), characterized in that: